Method for treating an imide organic solution bearing a sulphonyl group

ABSTRACT

The invention relates to a method of treating an impure organic composition of ammonium imide, one of the substituents of which imide ion is a sulfonyl carried by a perhalogenated, advantageously perfluorinated carbon, characterized in that said composition is subjected to a step of liquid-liquid extraction by means of an aqueous phase and containing, as impurity, at least one of the chemical species chosen from halides, sulfonates and sulfinates, in particular those whose sulfur is carried by a perhalogenated carbon.

The subject of the present invention is a technique for purifyingsulfonated imides from impure mixtures containing them. It relates moreparticularly to the purification of sulfonated imides in which thesulfur bearing the sulfonic functional group is attached to aperhalogenated, advantageously perfluorinated, atom. The imides carryinga sulfonic functional group, itself attached to a perhalogenated atom,although they have been known for ages, are currently developingrapidly. The reason for this is that these compounds are used asconstituent elements of lithium salts found in high-performancebatteries.

It should be recalled that imides are compounds having the functionalgroup below:

The imide ion functional group is only the deprotonated anionic form ofthe imide which has two substituents which are residues corresponding tooxygenated acids from which an OH group has been removed. The imides, orimide ions, covered by the present invention are those in which one ofthe Aci or Aci′ groups is a sulfonyl group, advantageously both Aci andAci′ groups are sulfonyls. The sulfonyl functional group, or one of thesulfonyl functional groups when there are two of them, is carried by aperhalogenated, advantageously perfluorinated, carbon. More particularlycovered are the imides containing a perhalogenated carbon on each of thesubstituents (here Aci and Aci′), said perhalogenated carbon beingadvantageously carried by an atom linked directly to the nitrogen.

These imide ions have in particular properties which have distinguishedthem as being value materials for the manufacture of batteries, whichproperties are, on the one hand, a very high acidity of the imide and,on the other hand, an absence of complexing power of the imide iontoward various cations.

These same properties make purification operations extremely difficultand delicate. The high acidity means a high dissociation and a highdissociation means a high solubility in polar media and in particular inwater. In addition, these highly acidic compounds form, in general,addition compounds with water and it is often very difficult to separatethese highly acidic compounds with water. The most common techniques forpurifying these imides are techniques of recrystallization, inparticular of recrystallization of their salts.

These imides are in general synthesized by the action of sulfonylhalides on trivalent nitrogen-containing derivatives carrying hydrogen(such as and in particular ammonia and amide) and in difficult cases,carrying a trialkylsilyl group. The sulfonyl group in general carries aperhalogenated carbon linked directly to the sulfur.

The sulfonyl halides currently most widely used areperfluoroalkanesulfonyl fluorides and chlorides and in particular C₁ andC₂ perfluoroalkanesulfonyl fluorides and chlorides.

Techniques for synthesizing this type of compounds are described inparticular in patent applications by the company Central Glass and bythe applicant.

The difficulty of this type of synthesis leads to the presence ofimpurities in significant quantities and in particular sulfonic andsulfinic acids corresponding to the sulfonyl acid chloride. There arealso found as impurities the starting nitrogen-containing derivative andthe amines which are often used for neutralizing the acids formed duringthe reaction, and the possible amines of a particular type which areused as catalysts.

Another source of these imides or of their salts, the imide ions, is therecycling of catalysts or of used batteries. There are found in theserecycling products the same type of impurities as those which have justbeen described above, except maybe those derived from the amines used ascatalysts (such as and in particular dialkylaminopyridines), it beingpossible for the other amines to be introduced in order to facilitatethe separation and the recovery of the constituents of the batteries.

Moreover, liquid/liquid extraction techniques are in general hardlypurifying, all these organic compounds are extracted in the organicphase; in addition, the compounds synthesized and/or the impurities andthe starting compounds are amphiphilic, play the role of a third solventand are even capable of having surfactant properties. The fatty aminesare additionally known to be amphiphilic.

In addition, in order to be able to carry out, under good conditions,purifications by (liquid-liquid) extraction, it is necessary, on the onehand, for the partition coefficients between, on the one hand, theproduct(s) to be retained and, on the other hand, the impurities to beremoved, to be very different and, on the other hand, for the partitioncoefficient of the impurity to be removed not to be too low in relationto the vector phase of said impurity.

In other words, if the organic phase φ_(o) is that from which it isdesired to remove the compound(s) considered as impurity (impurities)and to keep the desired compounds and the aqueous phase φ_(a), thewashing phase, then in order to avoid having excessive stream to handle,the partition coefficient of the impurity (φ_(a)/φ_(o)) considered,namely the ratio at equilibrium between the content of impurity per unitof quantity of material in the aqueous phase φ_(a) and the content ofimpurity per unit of quantity of material in the organic phase φ_(o),should be as high as possible and in any case at least equal to 1,advantageously to 2, preferably to 5. Of course, when the washing phaseis the organic phase φ_(o), the condition to be observed is theopposite, namely that it is the partition coefficient (φ_(o)/φ_(a))which should be high and at least equal to 1, advantageously to 2,preferably to 5.

It should finally be emphasized that the amphiphilic character of theacids containing polyfluorinated carbon(s) makes prediction of theirbehavior very difficult.

Accordingly, one of the aims of the present invention is to provide amethod which allows recovery and enrichment of solutions containing theimides or imide ions referred to above.

Another aim of the present invention is to provide a method of the abovetype which makes it possible to separate the imides, or the imide ions,from the sulfonic acids corresponding to the constituent sulfonyl of atleast one of the branches of the imide or imide ion functional group.

Another aim of the present invention is to provide a method of the abovetype which makes it possible to separate the imides or the imide ionsfrom the acids, their sulfinic salts corresponding to the reduction ofthe constituent sulfonyl groups of one of the branches of the imidefunctional group.

Another aim of the present invention is to provide a technique whichmakes it possible to separate the imides or the imide ions from thevarious halides which may have been released, which may be present inthe reaction mixture or recycling mixture. The halides most commonlyreleased are fluoride ions and/or chloride ions.

These aims, and others which will subsequently emerge, are achieved bymeans of a method of treating an impure organic composition of ammoniumimide, one of the substituents, advantageously both of the substituents,of which imide ion is a sulfonyl carried by a perhalogenated,advantageously perfluorinated carbon, characterized in that saidcomposition is subjected to a step of liquid-liquid extraction by meansof an aqueous phase and in that said impure organic compositioncontains, as impurities, at least one of the chemical species chosenfrom halides, sulfinates and sulfonates, in particular those whosesulfur is carried by a perhalogenated carbon.

It is appropriate to mention that previous trials dissuaded personsskilled in the art from using such techniques for carrying out extensivepurification. Indeed, the partition coefficients obtained from thereaction mixture were not at all favorable. A plausible explanation isthat there were too many organic compounds, in particular basiccompounds (salified or not, especially in hydrohalide form), in theaqueous phase. Following studies carried out by the inventors, asurprising aspect of the invention is that the partition coefficientsimprove with the course of the extraction.

Also, when a reaction mixture is to be treated, the first biphasicliquid/liquid system is not according to the invention. To systematizeand quantify this teaching, it is desirable to specify that it isadvisable to ensure that the aqueous phase contains by mass at least ⅔,advantageously at least ¾, preferably at least 8/10, more preferably9/10, of water. It is also preferable that the concentration of organicbase, most often amines, in the aqueous phase is at most equal to 1 mol;advantageously 0.5; preferably 0.2; more preferably 0.1 mol per kg orper liter (in molality or in molarity: the difference is quite small).

The expression perhalogenated carbon should be understood to mean acarbon of sp³ hybridization, bearing no hydrogen and containing, inaddition to its linkage with the chalcogen (here sulfur), at most 2,advantageously at most 1, radicals, all the other atoms being halogens;said radicals are advantageously chosen from electron-attracting groups(that is to say whose Hammett constant σ_(p) is greater than zero butthey are advantageously such that this constant is at least equal to0.15; preferably, to 0.2), especially when there are 2 thereof.

Thus, according to the present invention, a perhalogenated carbonadvantageously carries at least two halogens, these two halogens beingadvantageously at least partially and, preferably totally, fluorine; inother words a perhalogenated carbon is advantageously a methylenecarrying a fluorine and another halogen, which is advantageouslyfluorine.

An aqueous phase will be designated below by φ_(a) and an organic phaseby φ_(o).

The present invention may be carried out with the aid of a methodcomprising several liquid-liquid extraction steps by means of an aqueousphase, but at least one of these steps should be carried out at a basicpH, that is to say that the pH after extraction remains greater than 7.

It is preferable that at least one of the liquid-liquid extractions iscarried out such that the pH at the end of extraction (that is to saythe pH of the aqueous phase on leaving the extraction after the finaldecantation) is at least equal to 9, advantageously to 10, preferably,in particular when there are relatively large proportions ofperfluoroalkanesulfonic acids to be removed, at least equal to 11.5. ThepH may be regulated by adding base initially before contact with theorganic phase, such that the aqueous phase contains sufficient base tomaintain the final pH at the preceding values. As will be recalledbelow, the quantity of base, as equivalent, to be used is advantageouslyat least the sum of the quantity of base necessary to bring the aqueousphase (considered alone) to the desired pH and of the quantity, asequivalent, of acid impurities salified with the organic base. Thisquantity is advantageously increased by a quantity ranging from 0 to 20%of the imide to be recovered, preferably from 1% to 10%, more preferablyfrom 1 to 5%.

However, it is also possible to adjust the pH during contact so that itis always and especially in the end in the above region.

To obtain good results, it is preferable for said ammonium to have anumber of carbons at least equal to 5, preferably at least equal to 6,more preferably at least equal to 7.

To obtain good results, it is preferable to avoid the number of carbonsbeing too high, thus, it is preferable that the total number of carbonsof said ammonium is at most equal to 12, advantageously to 10. Accordingto the present invention, it is preferable that the ammonium carries atleast two hydrocarbon-based chains (that is to say containing bothcarbon and hydrogen, attached to the nitrogen by a secondary carbon ofsp³ hybridization). It is also preferable that said ammonium is aprotonated amine, said amine advantageously not being capable of beingalkylated.

As examples of amines which are not capable of being alkylated, theremay be mentioned tertiary amines advantageously containing, assubstituent(s), at least one hydrocarbon radical attached to thenitrogen by a secondary carbon. As example of amines which give goodresults, there may be mentioned the diisopropylethylamine, oftendesignated by its acronym (DiPEA). For it to be particularlyadvantageous to use the method according to the present invention, it isnecessary that the impure organic composition of ammonium imide ioncontains impurities chosen from sulfonates, in particular sulfonate ionsin which the sulfur is carried by a perhalogenated carbon. It is alsodesirable that the sulfonate ion whose sulfur is carried by aperhalogenated carbons contain no more than 3, advantageously no morethan 2 perfluorinated atoms per sulfonate functional group.

It is also desirable that said sulfonate ion, present as impurities, andhaving a sulfur carried by a perhalogenated carbon, contains at most 8,advantageously at most 5, preferably at most 4 fluorines per sulfonicfunctional group.

Among the impurities which can be removed by the method according to thepresent invention, there may also be mentioned the sulfinate ions whichare often generated during the reaction for synthesizing the imide ionsor which may be a product of decomposition of the imide ion. Thesesulfinate ions correspond to an anion which has the same empiricalformula as the corresponding sulfonyl radical, to within a negativecharge.

Thus, the method is perfectly suitable for the treatment of impureorganic compositions of ammonium imide ion containing a sulfinate ion,in particular a sulfinate ion whose sulfur is carried by aperhalogenated carbon.

This sulfinate ion whose sulfur is carried by a perhalogenated carbonadvantageously contains at most 3, preferably at most 2, perfluorinatedcarbons per sulfinate functional group, which functional group may alsobe designated by the expression “sulfinic functional group”.

It is also preferable that said perhalogenated carbon carried by thesulfinic, or sulfinate, functional group contains at most 8,advantageously at most 5, preferably at most 4, fluorines per sulfinicfunctional group.

According to the present invention, to have separations of excellentquality, it is preferable that the number of carbons of the sulfonatespresent in the imide ion or imide composition as impurities, is at mostequal to 12, advantageously to 6, preferably to 4.

It is preferable that the same constraint on the total number of carbonsapplies to the sulfinates present as impurities.

It is also preferable that the number of perhalogenated carbons of theimide ions to be purified is at least equal to that of the sulfinates orthe sulfonates which may be present in said composition.

It is even preferable that the number of perhalogenated carbons of saidimide ions is greater than that of the sulfinates and/or the sulfonatesfor the entire molecule.

It is also preferable that the perhalogenated carbons of said imide ionscontain in total at least 2, preferably at least 3, fluorines more thanthe sulfinates and/or the sulfonates, optionally present in saidcomposition, contain.

According to the present invention, it is preferable that said methodcomprises at least two steps or at least two series of steps; one of thesteps or one of the series of steps being carried out by means of anaqueous phase at natural pH, that is to say whose pH is that obtained bymere contact with a substantially pure aqueous phase (spring water ortap water, or even distilled water) or at a substantially neutral pH,that is to say a pH which is regulated such that its value at the end ofthe exchange is within the closed interval, that is to say comprisingthe limits 5 to 8. This aqueous phase may be subsequently designated byφ_(a1).

The other step, or the other series of steps, of liquid-liquid exchangeis carried out by an aqueous phase designated below by φ_(a2) whose pHis at least equal to 9, preferably to 10, more preferably to 11.5, inparticular when a sulfonate is present in the imide or imide ionsolution. Indeed, although all the acids present as impurities aresuperacids having an acidity close to that of the imides, in alkalinemedium, very different partition coefficients are observed.

When an initial aqueous phase is used which has a pH of between 3 and10, without buffer species (that is to say in which each speciespresent, capable of possessing buffering power in this region, is at aconcentration at most equal to 10⁻², advantageously to 10⁻³, it is evenpreferable that the sum of said species satisfies this condition), ingeneral spring water, distilled water, deionized water or water ofequivalent purity, the pH is set during the bringing into contact, thispH is called natural pH. The most common conditions for bringing intocontact with a neutral aqueous phase or at natural pH should beindicated. These conditions are summarized below:

-   -   temperature: between 0 and the boiling temperature of the        solvent used (at the operating pressure), preferably between 10        and 30° C.;    -   any pressure, preferably at atmospheric pressure for reasons of        ease of implementation;    -   mass/aqueous phase and organic phase ratio (ratio of the flow        rates per unit of time in the case of continuous operations):        between 0.1 and 10;    -   implementation by succession of mixing/decantation/drawing off        batch or by continuous operation (extraction column or series of        mixers-decanters);    -   operation by batch or continuous methodical washings (cocurrent        or countercurrent).

As regards bringing into contact with a basic aqueous phase, it may bestated that the most common conditions are similar, or even identical(apart from the pH), as indicated below:

-   -   temperature: between 0° C. and the boiling temperature of the        solvent used (at the operating pressure), preferably between 10        and 30° C.;    -   pressure (cf. above for bringing into contact with the neutral        aqueous phase), preferably at atmospheric pressure;    -   ratio between the masses of aqueous phase and of organic phase        (ratio of the flow rates per unit of time in the case of        continuous operations): between 0.1 and 10;    -   pH: between 10 and 12.5; compromise between yield and efficacy        of removal of the impurities; implementation by one or more        successions of mixing/decantation/drawing off unit operations or        by continuous operation (extraction column or series of        mixers-decanters).

These questions of use of common technologies are detailed below.

The liquid/liquid exchange techniques are techniques well known to aperson skilled in the art which may be mixers-decanters in series andoperating countercurrentwise. They can also use exchange columns.

In the case of a countercurrent implementation in mixers-decanters or incolumns, with an aqueous stream playing the role of the neutral phaseand of the basic phase, the phase φ_(a2) corresponds to the incomingphase and the phase φ_(a1) corresponds to the outgoing phase once theaqueous phase has passed through the series of mixer-decanters.

It is preferable that there is a solvent, this solvent may be that ofthe initial impure composition, it may also be a solvent which is added,and finally this may be a solvent which has been used to dissolve theimide ion and its impurities for the exchange.

The solvents which give the best results are solvents which have an atomdoublet to give, it being possible for this atom to be a halogen,advantageously fluorine, a chalcogen, advantageously oxygen, or an atomof the nitrogen column.

The latter case is not preferred because this solvent has a dual usewith the amines, which can make the method cumbersome. It is alsopreferable that the solvent is such that the atom carrying the doubletto be given is not hindered, that is to say that it does not carry morethan one secondary or tertiary carbon radical.

Thus, there may be mentioned the aliphatic chlorinated derivatives suchas chlorinated derivatives such as methylene chloride ortrichloroethylene, these chlorinated derivatives advantageously have atleast one hydrogen. There may also be mentioned the aromatic halogenatedderivatives and there may also be mentioned the unhindered ethers. Thus,ethyl ether gives good results, isopropyl methyl ether also gives goodresults; on the other hand, diisopropyl ether gives poor results. Thearomatic hydrocarbons such as benzene and toluene also give very poorresults.

The main aim of the bringing into contact with the aqueous phase φ_(a1)is to remove the halides such as fluoride, chloride, or even bromide.The second step using a basic pH is designed to remove the sulfinatesand the sulfonates. A single solution may be used, provided that it issufficiently basic.

To obtain a good rate of removal of the sulfonic acids, it is preferableto be at a pH at least equal to 11.5.

During the basic washing, the quantity of base to be used isadvantageously at least the quantity of base necessary to bring theaqueous phase (considered alone) to the desired pH, increased by thequantity, as equivalent, of the acid impurities salified by the organicbase. This quantity is advantageously increased by a quantity rangingfrom 0 to 20% of the imide to be recovered, preferably from 1% to 10%,more preferably from 1 to 5%.

The recovering of the purified imide from the organic phase may becarried out in various ways. Thus, it is possible to distil the solventand the possible excess amine in order to recover the ammonium imideafter purification. It is also possible to distil on a solid or liquidbase which is stronger than the amine combined with said ammonium and tothereby recover the triflimide corresponding to the base.

However, according to a preferred embodiment of the present invention,the organic phase is subjected to a basic solution (or even asuspension), that is to say whose pH is greater than 12.5,advantageously greater than 13.

Thus, the organic solution freed of these impurities may be neutralizedwith a relatively strong base, that is to say whose pKa is at leastequal to 12.5, preferably at least equal to that of lithium hydroxide.This final neutralization makes it possible to completely release theamine corresponding to the ammonium, and to make the triflimide salt ofthe metal corresponding to the cation of the base. In the washing steps,it is also preferable to ensure that the quantity of base added is suchthat the final pH is less than 12.5. Thus, it is preferable to verifythat the final aqueous purification phase (φ_(a2) in the case of twoaqueous phases) has a pH which is not too basic and advantageously atmost equal to 12.5.

The aqueous phase containing the imide ion may be evaporated, forexample freeze-dried.

Overview of the meaning of the abbreviations used:

-   TFSILi: lithium bistrifluoromethanesulfonimide (CF₃SO₂)₂NLi-   TFSI,: trialkylammonium-   NR₃ bistrifluoromethanesulfonimide-   TFSA: trifluoromethanesulfdnamide CF₃SO₂NH₂-   TFSCl: trifluoromethanesulfonyl chloride CF₃SO₂Cl-   TFSIH: bistrifluoromethanesulfonimide-   CF₃SO₂ ⁻: trifluoromethanesulfinate (triflinate, TFSH)-   CF₃SO₃ ⁻: trifluoromethanesulfonate (triflate, TFSOH)-   DIPEA: diisopropylethylamine-   NEt₃: triethylamine-   DMAP: 4-dimethylaminopyridine

By way of teaching, for example, it is possible to detail theimplementation of a process sequence applied to the synthesis of lithiumtriflimide.

In this implementation, the method of synthesis of lithiumbistrifluoromethanesulfonimide (TFSILi) comprises the following steps:

-   -   reaction of trifluoromethanesulfonyl chloride (TFSCl) with        ammonia to give a mixture, here a reaction mixture, which will        be taken up by the method of treatment according to the        invention;    -   removal of the coproducts and/or of the impurities by        liquid-liquid extraction according to the invention of the        impure mass;    -   recovery of the imide ion; and optionally:    -   removal-recovery of the solvent;    -   recovery of the DIPEA by action of a base.        Preferred Operating Conditions for Optional Steps        Removal of the Solvent    -   pressure between 10 hectoPa and 5 bar;    -   the temperature is determined by the pressure;    -   batch or continuous;    -   the solvent is recovered by condensation so as to be recycled.        Recovery of the DIPEA by Action of a Base    -   by azeotropic distillation        -   pressure between 10 hectoPa and 5 bar;        -   temperature determined by the pressure;        -   base/TFSI anion molar ratio greater than 1,        -   preferably between 1.01 and 1.2.    -   by decantation base/TFSI anion molar ratio at least equal to 1        and advantageously at most equal to 3/2, preferably 1.2;        -   temperature advantageously greater than 10° C. in order to            facilitate the decantation.

The following nonlimiting examples illustrate the invention:

Exemplification of the Various Steps

The examples given below to illustrate the various steps were chosen fortheir demonstrative qualities. For reasons evident to a person skilledin the art, they were not all carried out on the same scale ofquantities because some technologies used require large quantities forsuccessful implementation. That does not in any way detract from thedemonstration of the feasibility of the series.

Exemplification of the Reaction of the Starting Composition

EXAMPLE 1

The apparatus used comprises:

-   -   a jacketed 1 liter reactor equipped with central stirring;    -   a hot/cold bath which makes it possible to maintain the reaction        mass at −30° C. if necessary;    -   a supply of ammonia gas by immersing using a 1 liter pressurized        ammonia bottle;    -   a dry ice trap in series on a set of N₂ valves which make it        possible to maintain the reactor at a pressure close to        atmospheric pressure in the laboratory;    -   an injection of CF₃SO₂Cl at a controlled flow rate via a        propelled syringe.

The entire apparatus is placed in a ventilated hood.

Dichloromethane (490 g), DIPEA (221 g) and DMAP (3.5 g) are loaded intothe 1 liter reactor.

The desired quantity of ammonia (9.7 g) is loaded by absorption at −15°C. into the dichloromethane base from the bottle by means of theplunger. The exact quantity loaded is determined by weighing and/ormeasuring the flow rate. The condenser, cooled with dry ice, ensuresthat there is no loss of ammonia outside the reactor. The solution ofCF₃SO₂Cl at 50% in dichloromethane (383.4 g) is then injected via apropelled syringe while the temperature of the reaction mass ismaintained between −10 and −5° C.: the duration of the pouring 3 hours.The temperature is then allowed to return to room temperature (1 hour).The reaction mass is then washed with about 150 g of water so as to havetwo easily analyzable homogeneous phases. About 1002.7 g of organicphase and 240.3 g of aqueous phase are recovered.

The analysis of the composition of the organic and dichloromethanephases by ion chromatography gives the following results: PartitionPhase Organic Aqueous coef. φ_(o)/φ_(a) weight % % Cl— 1.9 8.5 0.23CF₃SO₂ ⁻ 0.33 0.07 4.7 CF₃SO₃ ⁻ 1.2 0.2 5.7 (CF₃SO₂)₂N⁻ 14.8 nd

These partition coefficients are scarcely favorable for thepurification.

EXAMPLE 2

Example 1 is repeated, except that all the dichloromethane (680 g) isloaded into the reactor at the beginning of the operation. 268.6 g ofDIPEA, 4.2 g of DMAP and 12.0 g of ammonia are then loaded. The CF₃SO₂Cl(233.2 g) is then injected into the reaction medium by means of apropelled syringe. The duration of injection is 2 h 30 min during whichthe reaction mass is kept at −20° C. The temperature is then allowed toreturn to room temperature (1 hour). The reaction mass is then washedwith about 300 g of water so as to have two, easily analyzablehomogeneous phases. About 1040 g of organic phase and 445 g of aqueousphase are recovered. Mass of the % by mass phases F⁻ Cl⁻ CF₃SO₂ ⁻CF₃SO₂NH₂ CF₃SO₃ ⁻ (CF₃SO₂)₂N⁻ φ_(o) 1040 g 0 1.5 0.2 0.05 0.6 18 φ_(a) 445 g 0 7.2 0.05 0.01 0.08 Partition 0.2 4 5 7.5 coef. φ_(o)/φ_(a)

The partition coefficients are here very unfavorable for thepurification.

Exemplification of the Washes by Liquid-Liquid Extraction

EXAMPLE 3 Extraction at Neutral or Natural pH

This example illustrates the way to carry out the aqueous washes toremove the chloride ions.

Example 1 is repeated, except that the ammonia is loaded at a coldertemperature (−20° C.), which makes it possible to load a larger quantityof ammonia. The DIPEA, TFSCl and DMAP load is modified proportionately.The total quantity of dichloromethane loaded is unchanged. Afterreaction, the reaction mass is washed with 300 g of water. Afterdecantation, the aqueous phase is removed from the reactor and 300 g ofwater are added. The whole is stirred for ¼ of an hour and thendecantation is also allowed to proceed for ¼ of an hour. The organic andaqueous phases are analyzed by ion chromatography and then the aqueousphase is again removed. This operation is repeated four times. Thevariation of the composition of the different phases is illustrated inthe tables below.

It is observed that the chloride ions which are troublesome for theremainder of the method and for the quality of the final product areremoved from the organic phase with minimal losses of the TFSI anionwhose value is to be enhanced. Chemical species Phase F⁻ Cl⁻ CF₃SO₂ ⁻CF₃SO₂NH⁻ CF₃SO₃ ⁻ TFSI⁻ Organic 0.001 2 0.2 0.05 0.6 24 phase 1^(st)wash Aqueous 0.001 7.4 0.04 0.05 0.08 0.05 phase 1^(st) wash Organic0.001 0.7 0.2 0.06 0.6 26.5 phase 2^(nd) wash Aqueous 0.001 3.1 0.060.03 0.09 0.18 phase 2^(nd) wash Organic 0.001 0.2 0.15 0.03 0.6 27.5phase 3^(rd) wash Aqueous 0.001 1.2 0.08 0.015 0.1 0.06 phase 3^(rd)wash Organic 0.001 0.03 0.1 0.05 0.5 27.8 phase 4^(th) wash Aqueous0.001 0.3 0.1 0.017 0.2 0.1 phase 4^(th) wash

Ratio between the partition coefficient of the TFSI and that of thechemical species Partition coefficient φ_(o)/φ_(a) considered F⁻ Cl⁻CF₃SO₂ ⁻ CF₃SO₂NH⁻ CF₃SO₃ ⁻ TFSI⁻ F⁻ Cl⁻ CF₃SO₂ ⁻ CF₃SO₂NH⁻ CF₃SO₃ ⁻TFSI⁻ 1^(st) wash 1 0.270 5 1 7.5 480 480 1776 96 480 64 1 2^(nd) wash 10.226 3.333 2 6.667 147.2 147.22 651.9 44.17 73.61 22.08 1 3^(rd) wash 10.167 1.875 2 6 458.3 458.33 2750 244.44 229.17 76.39 1 4^(th) wash 10.1 1 2.941 2.5 278 278 2780 278 94.52 111.2 1

EXAMPLE 4

This example illustrates the way to wash the reaction mass at basic pHto remove the impurities such as trifluoromethanesulfonate ortrifluoromethanesulfinate.

A reaction mass having a mass of 792 g, obtained as in Example 3, thatis to say washed beforehand so as to be freed of chloride ions, isplaced in the 1 liter reactor described above, but equipped with a pHprobe, and after having evaporated part of the dichloromethane solvent(composition organic phase 1), 300 g of water and 26 ml of 2N sodiumhydroxide are added with stirring so as to obtain a pH of 10.8.Decantation is allowed to proceed for ¼ of an hour and the aqueous phaseis withdrawn. 300 g of water are again added and the pH is adjusted to10.8, with stirring, with this time 8.5 ml of 2N sodium hydroxide. Afterdecantation, the aqueous phase is withdrawn.

The weight and the composition of the various phases are given in thetables below.

It is observed that in the organic phase 3, the content oftrifluoromethanesulfonic anion and of trifluoro-methanesulfinic anion isless than 0.06% and 0.01%, respectively. This demonstrates that afterthree basic washes, a dichloromethane solution of the practically pureTFSIH/DIPEA complex is obtained. weight F⁻ Cl⁻ CF₃SO₂ ⁻ CF₃SO₂NH⁻ CF₃SO₃⁻ TFSI⁻ Organic 792 <10⁻³    0.04 0.1 0.1 0.6 30.7 phase 1 Organic 767<10⁻³    0.006 0.01 0.01 0.16 30.9 phase 2 Aqueous 342 <10⁻³    0.07 0.20.1 1 1.4 phase 2 Organic 746 <10⁻³    0.004 0.01 0.01 0.06 30.7 phase 3Aqueous 321 <10⁻³ <10⁻³ 0.02 0.01 0.2 1.1 phase 3

Ratio between the partition coefficient of the Partition coefficientφ_(o)/φ_(a) TFSI and that of the chemical species considered weight F⁻Cl⁻ CF₃SO₂ ⁻ CF₃SO₂NH⁻ CF₃SO₃ ⁻ TFSI⁻ F⁻ Cl⁻ CF₃SO₂ ⁻ CF₃SO₂NH⁻ CF₃SO₃ ⁻TFSI⁻ 1^(st) wash 2.24 1.00 0.09 0.05 0.10 0.16 22.07 22.07 257.50441.43 220.71 137.95 1.00 2^(nd) wash 2.32 1.00 n.s. 0.50 1.00 0.3027.91 27.91 n.s.  55.82  27.91  93.03 1.00

1-22. (canceled)
 23. A method of treating an impure organic composition of ammonium imide, one of the substituents of which imide ion is a sulfonyl carried by a perhalogenated, optionally perfluorinated carbon, said process comprising the steps of: a) submitting said composition to a liquid-liquid extraction by means of an aqueous phase and containing, as impurity, at least one of the chemical species selected from the group consisting of halides, sulfonates and sulfinates; and b) recovering said ammonium imide.
 24. The method as claimed in claim 23, wherein the species have a sulfur carried by a perhalogenated carbon.
 25. The method as claimed in claim 23, wherein the aqueous phase has a pH adjusted to a value at least equal to 9 when a perfluorosulfonic acid is present.
 26. The method as claimed in claim 23, wherein said ammonium has a number of carbons at least equal to 5 and at most equal to
 12. 27. The method as claimed in claim 23, wherein the ammonium carries at least two hydrocarbon-based chains, containing both carbon and hydrogen, attached to the nitrogen by a secondary carbon of sp³ hybridization.
 28. The method as claimed in claim 23, wherein said ammonium is a protonated amine.
 29. The method as claimed in claim 28, wherein said ammonium is an alkylated protonated amine.
 30. The method as claimed in claim 29, wherein said ammonium is a protonated tertiary amine.
 31. The method as claimed in claim 30, wherein said ammonium is a protonated tertiary amine which cannot be quaternized.
 32. The method as claimed in claim 23, wherein said impure organic composition of ammonium imide contains a sulfonate ion whose sulfur is carried by a perhalogenated carbon.
 33. The method as claimed in claim 32, wherein said perhalogenated carbon contains at most three perfluorinated carbons per sulfonate functional group.
 34. The method as claimed in claim 32, wherein said perhalogenated carbon contains at most 8 fluorines per sulfonate functional group.
 35. The method as claimed in claim 23, wherein said impure organic composition of ammonium imide ion contains a sulfinate ion whose sulfur is carried by a perhalogenated carbon.
 36. The method as claimed in claim 35, wherein said perhalogenated carbon contains at most three perfluorinated carbons per sulfinate functional group.
 37. The method as claimed in claim 36, wherein said perhalogenated carbon contains at most 8 fluorines per sulfinate functional group.
 38. The method as claimed in claim 23, wherein said imide ion carries two sulfonyl functional groups of which at least one is carried by a perfluorinated carbon.
 39. The method as claimed in claim 38, wherein said imide ion carries two sulfonyl functional groups, both carried by a perfluorinated, carbon.
 40. The method as claimed in claim 23, wherein the number of carbons of the sulfonates is at most equal to
 12. 41. The method as claimed in claim 23, wherein the number of carbons of the sulfinates is at most equal to
 12. 42. The method as claimed in claim 23, wherein sulfinates and/or the sulfonates are present in said composition and the number of perhalogenated carbons of said imide ions is at least equal to that of the sulfinates and/or the sulfonates present in said composition.
 43. The method as claimed in claim 42, wherein the number of perhalogenated carbons of said imide ions is greater than that of the sulfinates and/or sulfonates present in said composition.
 44. The method as claimed in claim 42, wherein the number of perhalogenated carbons of said imide ions contains at least 2 fluorines more than the sulfinates and/or the sulfonates present in said composition, contain.
 45. The method as claimed in claim 23, wherein the liquid-liquid exchange step a) is carried out by an aqueous phase Φ_(a1) at a pH between 5 and 8, and further comprising at least one more liquid-liquid exchange step a′) carried out by an aqueous phase Φ_(a2) whose pH is at least equal to
 9. 